The present invention relates to a method and device for automatically splicing yarn on a ring spinning machine, and more particularly to such a method and device wherein a broken end of yarn to be spliced is drawn by suction into a tube in position for splicing and a sensor senses the presence of the yarn end in the tube to initiate a splicing operation.
It is known in yarn splicers for ring spinning machines to utilize a jet of air to blow a broken yarn end from a bobbin of yarn and utilize suction to draw the yarn end into a suction tube for positioning the yarn end for splicing.
Conventionally, a sensor is located in the suction tube to sense the presence of the yarn end and in response to the sensing the device terminates the air jet and initiates the subsequent splicing process. Such a sensor can be, e.g., a mechanical feeler or an optical sensor.
The suction in the suction tube must be of sufficient force to draw they yarn end that has been blown loose by the air jet and draw it into a bell at the end of the suction tube and then into the tube in position for splicing. However, the suction must not be so strong that it damages the yarn end, e.g., by untwisting it or disintegrating the end so that it is shortened to a length less than desirable for splicing. It has been difficult to balance the suction to obtain optimum engagement and positioning of the yarn end and yet not damage or disintegrate the yarn end.